Also shameless self advertising http://www.hardwarewallet.com - available soon, after some lengthy redesigning process, target price around 10
I don't see a display; how does the user verify the transaction details haven't been modified by malware before signing the transaction?
You submit the transaction to the dongle, then remove it, then insert it again into the same computer and a different application (f.e. Windows login screen) / another device supporting HID keyboards, depending how much you fear being compromised, the dongle types (as a keyboard) a summary of the transaction and a unique PIN code, finally you plug it back into the original computer (or just remove it / plug it back again) then type this PIN code to validate the transaction.
and it's easier than it sounds
Ah, clever. I'll buy one when they are available. Seems like you could use a modified version of this to verify transactions/account changes on an exchange or mining pool.